This invention relates to a method for detecting brightness signals from a multiplicity of light-sensitive sensor elements, in particular from CCD lines or arrays.
DE 42 28 299 A1, for example, describes as state of the art in column 1 starting in line 40 a method of this kind in which the brightness signals are amplified in such a way that an A/D converter which digitizes the amplified brightness signals works in its permissible working range. A method of this kind is also referred to there as signal conditioning. Resetting of the amplifier results here in a slowing down of the measurement because of the operating delay in the amplifier. In order to be able to image on the working range of the A/D converter the entire dynamic range of the brightness signal, that is both the lower and the upper limit of the brightness signal, the gain factor is preferably corrected pixel by pixel. In particular when correcting the gain factor pixel by pixel, each pixel must be reset on the basis of a maximum or minimum gain factor.
Furthermore, DE 197 04 793 A1 also describes an optical transmission and receiving device in which optical guiding means are provided within the housing in front of a translucent cover between transmission unit and receiving unit so that the light component reflected at the translucent cover of the transmission device is guided to the receiving unit, thereby making it possible to establish that the transmission unit is functioning and whether the translucent cover is dirty.
Moreover, from EP 0 150 847 B2 a lighting control equipment is known for facsimile devices, scanners, photocopying machines or other similar optical equipment with an optical transmission and receiving system, where the lighting time of the light source of the transmitter is adjusted according to the brightness received at the receiver.